This research is designed to make electrical stimulation of the retina a useful tool for studying retinal physiology and pathology. It will determine the site of action of such stimulation and will contribute to the understanding of retinal synaptic physiology. Focal electrical stimulation of retinas will be the major methodological technique used in this research. BIBLIOGRAPHIC REFERENCES: Knighton, R.W.: An electrically evoked slow potential of the frog's retina. Properties of response. J. Neurophysiol. 38:185-197, 1975. Knighton, R.W.: Modification of the frog's electroretinogram by transretinal direct current. J. Neurophysiol. 38:210-216, 1975.